Waveguide rotary joint



1961 F. E. HASSELD, JR 2,973,493

WAVEGUIDE ROTARY JOINT Filed Nov. 30, 1959 ////QV FEM/K 5 52121212? United rates Fatent @r WAVEGUIDE ROTARY J W1 Frank E. Hasseld, Jr., 263 S. Emerson Ave, Indianapolis, Ind.

Filed Nov. 30, 1959, Ser. No. 856,310

6 t'jlaims. (Cl. 333-98) (Granted under Title 35, US. Code (1952), see. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This invention relates to microwave energy guiding or conveying systems and more particularly to means for coupling waveguides between which relative movement is required. In transitions from a fixed waveguide to a waveguide section having rotational movement with respect to the fixed waveguide, the prior practice has been to use a coaxial line in the transition from one waveguide section to the other. This practice has a number of disadvantages and particularly the disadvantage of restricting the bandwidth which can be used to the extent that a bandwidth of 1000 megacycles is considered very good. Another disadvantage is the fact that more energy loss problems were encountered, particularly the loss produced by the dielectric probe support of the coaxial portion of the rotary joint. Moreover, it was necessary to construct parts at very close tolerances to provide proper impedance matching. The result was a high cost of fabrication and difliculty in duplicating parts so that all assembled joints would correspond electrically. A final disadvantage is that the power handling capabilities of conventional construction are poor.

The present invention utilizes a housing being adapted to connect to one waveguide element and a core assembly inside the housing and rotatably mounted therein which is adapted to be connected to another section of waveguide so that the two sections of waveguide are movable and more specifically rotatable with respect to each other. The structure of the present invention makes possible the transition from one waveguide section to another which is rotatable with respect to the first, with no change in the voltage standing wave ratio (VSWR) of the energy transmitted through it over a broad band of microwave frequencies. It requires no matching and eliminates the transition from waveguide to coaxial line and back to waveguide. Accordingly, it is an object of the present invention to provide a waveguide rotary joint having ability to transmit microwave energy at all frequencies in a broad band of frequencies with no change in the voltage standing wave ratio. It is another object to provide a waveguide rotary joint requiring no matching. It is another object to provide a waveguide rotary joint which eliminates going from waveguide to coaxial line and back to waveguide and it is another object to provide a waveguide rotary joint which has good power handling capabilities.

Other objects and advantages of this invention will be realized and appreciated when the description of a preferred embodiment thereof is read and reference made to the several figures of drawings in which like reference characters designate like parts throughout the figures wherein:

Figure 1 shows in perspective a subassembly of the core member;

Patented Feb. 28, 1961 Figure 2 shows in perspective a partial assembly of the invention including the housing;

Figure 3 shows in perspective another part of the core member; and

Figure 4 shows a cross-section of the complete assembly.

Referring to Figure 1 there is shown a lower chamber defining disc 11 having in the outside diameter thereof a groove 12 which performs the function of a choke in the waveguide rotary joint assembly. Mounted on the top of this chamber defining disc is a separating block 13 including an extension 14 which may be a separate part or integral with the block 13. The block 13 in assembly is fastened to the disc 11 by means of fasteners through the holes designated by reference character 15. The extension 14 has an arcuate face 16 which blends into a slot 17 in the block 13 providing a path for the microwave energy as will become more apparcut as the disclosure proceeds. The block 13 has a primary axis which is coaxial with the disc 11 in assembly and the outside diameter of the disc 11 is flush with the outside of the extension 14 in which there are also choke grooves 18.

Figure 2 shows a housing 21 having a cylindrical shape and an opening designated A in the side thereof to provide a passageway for microwave energy to or from a section of waveguide (not shown) which could be attached to the housing in any suitable manner. The housing has a recess 22 in one end to receive a bearing which may be of any suitable design. A finger or guiding fillet 23 which may be fastened to the wall of the housing after assembly of the core member into the housing, is designed to provide a correct transition between the waveguide opening A and the chamber which is defined by the core member and housing assembly as will be shown. The finger 23 normally has one or two choke grooves 24 in its tip side 25 to prevent leakage of micro wave energy in assembly.

Figure 3 shows a single chamber defining disc 26 which may be fastened to the top of separating block 13, shown in Figure 1, by some suitable fasteners such as bolts through the holes designated by reference character 27 in such manner that the rectangular slot or hole B through the disc co-operates with the slot 17 in the separating block 13 of Figure 1. The disc 26 has choke groove 28 similar to those in the disc 11.

Figure 4 shows a cross-section of the assembly of the core member into the housing and an annular chamber 31 which is defined by the housing walls, the separating block 13 and the chamber 31 defining discs 26 and 11. The rotatable mounting of the core member with respect to the housing as well as the retention thereof in the housing is provided for in this embodiment by a ball bearing assembly 32 and a retaining ring 33 and the press fit of the bearing assembly 32 into the housing 21. The choke grooves form an energy confining boundary for the chamber 31.

In the assembly, microwave energy entering opening A in the housing wall is directed by finger 23 into the annular chamber 31. It is picked up by extension 14 of separating block 13 and guided into slot 17 of the block. There it changes direction and passes up through the hole B in disc 26 to exit. In another application of this invention it may be desirable to have energy enter hole B and exit from opening A. In either application a broad band of frequencies can be accommodated. For example the rotary joint is capable of operating over the entire X, Kn, and Ka bands without causing a change in the voltage standing wave ratio of the energy passing through it.

The spatial disposition of this invention does not atfect its operation. The relative rotation between the housing and core member is limited only by mechanical interference betweenthe finger 23 and the separating block extension 14.

While the above disclosure of the structure of the preferred embodiment of this invention has reference to that shown in the Figures it is to be understood that many variations of this invention may be practiced Without deviating from the scope thereof, which I wish to be limited only by the appended claims.

What is claimed is:

1. Apparatus for transmission of microwave energy from one microwave means to another microwave means rotatably related to said one microwave means, said apparatus comprising: a housing having a wall of cylindrical shape and at least one open end, said housing being adapted to receive bearing means and said wall having a waveguide opening to accommodate passage of microwave energy through said apparatus; a first chamber defining means having a substantially flat face extending radially equidistantly from an axis perpendicular to said face, said face having a diameter approximately equal to the inside diameter of said housing and said first chamber defining means having bearing means thereon to provide a bearing of said first chamber defining means in said housing; a separating block having, a principal axis, two parallel faces perpendicular to said axis and having a periphery at a radius less than the radius of said first chamber defining means and interrupted at two points, the first of which defines the intersection of the periphery with a first edge of a slot extending inwardly from the periphery which slot has a second edge extending parallel to said first edge and outwardly and changing to a curve and continuing to a terminal edge at a radius equal to the radius of said first chamber defining means, the continuation forming one side of a peninsular extension of said block, the second point defines the intersection of the said periphery with another side of said extension, said another side extending outwardly to a distance at a radius from said axis equal to that of said first chamber defining means and said extension having a third side outward from said axis at a radius equal to that of said first chamber defining means and flush with the periphery thereof; a second chamber defining means having a substantially flat face extending radially equidistantly from an axis perpendicular to said face, said face having a diameter approximately equal to the inside diameter of said housing and said second chamber defining means having a slot therethrough for communication with the slot in said separating block, said separating block and said first and second chamber defining means being aflixed together coaxially within said housing, and a finger fixable to said housing adjacent to said waveguide opening and extending into the annular chamber defined by said first and second chamber defining means, said separating block and said wall to provide a transition for wave energy passing through said apparatus when said housing, said finger, said first and second chamber defining means, and said separating block and extension are in assembly, whereby microwave energy may be transmitted from one waveguide to another having a rotary motion with respect to said one waveguide and without changing the voltage standing wave ratio in the transmission.

2. Apparatus for transmission of microwave energy from one microwave means to another microwave means rotatably related to said one microwave means, said apparatus comprising: a housing having a wall of cylindrical shape, a large opening at one end and a small opening at the other end, said small opening adapted to receive bearing means and said wall having a waveguide opening for the passage of enegy between said apparatus and a waveguide; a first chamber defining means having a substantially flat face extending radially equidistantly from an axis perpendicular to said face, said face having a diameter approximately equal to the inside diameter of said housing, and said first chamber defining means having bearing means thereon to enter said small opening in said housing to provide a bearing of said first chamber defining means in said housing; a separating block having, a principal axis, two parallel faces perpendicular to said axis and having a periphery at a radius less than the radius of said first chamber defining means and interrupted at two points, the first of which defines the intersection of the periphery with a first edge of a slot extending inwardly from the periphery which slot has a second edge extending parallel to said first edge and outwardly to intersect a circle of a diameter equal to that of the periphery of said separating block and continuing therefrom arcuately and terminating at a radius from said principal axis equal to the radius of said first chamber defining means, thearcuate continuation forming one side of a peninsular extension of said block, the second point defining the intersection of the said periphery with another side of said extension said another side extending outwardly to a distance at a radius from said axis equal to that of said first chamber defining means and said extension having a third side outward from said axis at a radius equal to that of said first chamber defining means and flush with the periphery thereof; a second chamber defining means having a substantially fiat face extending radially equidistantly from an axis perpendicular to said face, said face having a diameter approximately equal to the inside diameter of said housing and said second chamber defining means having a slot therethrough for communication with the slot in said separating block, said separating block and said first and second chamber defining means being afiixed together coaxially within said housing, and a finger afiixed to said housing within its said wall adjacent to said Waveguide opening and into the annular chamber defined by said chamber defining means said separating block and said wall to provide a transition for wave energy passing through said apparatus when said housing, said finger, said first and second chamber defining means, and said separating block with said extension are in assembly, whereby a broad band of microwave energy may be transmitted'from one waveguide to another having a rotary motion with respect to said one waveguide and without changing the voltage standing Wave ratio during transmission.

3. The apparatus of claim 2 wherein each said chamber defining means and said extension and said finger has therein means for avoiding leakage of microwave energy in assembly.

4. The apparatus of claim 2 wherein each said chamber defining means has in its periphery, groove means whereby microwave energy is confined to said annular chamber in assembly.

5. The apparatus of claim 4 wherein said third side has grooves therein for confining microwave energy in said annular chamber in assembly.

6. A rotary joint for microwave apparatus said joint comprising: a housing having a wall of cylindrical shape and having openings at each end and a first waveguide opening in said wall; a core means located within said housing and rotatably afiixed thereto by a bearing, said core means having a principal axis concentric with the axis of said housing, a first disc having an axis concentric with said principal axis and a second waveguide opening therethrough at its axis; a separating block abutting a substantally fiat side of said disc toward the inside of said housing, said block being substantially cylindrical in shape and having a periphery of principal diameter less than said disc, said periphery being interrupted by an extension of said block extending to an edge at a radius equal to the radius of said disc said edge continuing through an are at said radius, said block having a passage therein adjacent to said extension and to said second waveguide opening in awsaos said disc abuttingly attached thereto and communicating therewith said passage having the side adjacent to said extension blending into a curved surface and continuing to intersect said are at said radius forming a comer; a second disc coaxial with said first disc and abutting said block and, in cooperation with said block and said first disc and the wall of said housing, forming an annular chamber for the passage of microwave energy; and a guiding fillet removably aflixed to said wall within said housing adjacent to said first waveguide opening and intersecting 10 2,784,383

the entire cross sectional area of said chamber whereby microwave energy can be conducted from a fixed waveguide to a movable waveguide with no change in voltage standing wave ratio and for a broad band of frequencies.

References Cited in the file of this patent UNITED STATES PATENTS Habich May 13, 1952 Zaleski Mar. 5, 1957 

